OAKDALE — A salmon nosed around the gravel in a Stanislaus River stretch east of Oakdale, guarding eggs she had just laid.
The fish had swum this fall from the Pacific Ocean, her home for the past few years, and found spawning gravel restored by humans to suit her needs.
"It's rewarding," said Jason Guignard, a consulting biologist who helped on the project, during a mid-December visit to the site.
"This is what it's about," agreed John Davids, engineer for the Oakdale Irrigation District, which paid half of the $1.1 million cost.
The OID, which gets its water from the Stanislaus, is one of many parties involved in the effort to restore chinook salmon in the Northern San Joaquin Valley.
They used to swim by the tens of thousands on the Stanislaus, Tuolumne, Merced and San Joaquin rivers and in far greater numbers on the Sacramento River and its tributaries.
This fall's count of salmon returning from the sea shows mixed results in the Northern San Joaquin Valley.
On the Stanislaus as of Dec. 16, 7,019 fish had passed through the temporary weir that spans the stream near Riverbank. At the same point in 2007, just 403 had passed through.
On the Tuolumne, the count through Dec. 16 stood at 2,075, down from 2,773 at the same point last year.
"We're just continuing to see problems with not enough flow and not enough habitat," said Patrick Koepele, deputy executive director of the Tuolumne River Trust. "We were hopeful that last year was the beginning of an upward swing, so we're disappointed."
On the Tuolumne
The Tuolumne is doing better than in 2009, when a mere 257 salmon passed through the weir near La Grange, said Walt Ward, assistant general manager for water operations at the Modesto Irrigation District.
Despite the drop from last year, he said, the females that did return are larger on average and contain more eggs, which could boost reproduction.
The MID and the Turlock Irrigation District keep close watch on the Tuol-umne salmon counts because another crash could bring pressure to release extra water from Don Pedro Reservoir.
The counts on both rivers are conducted from October to December by FISHBIO, a consulting company based in Oakdale that also worked on the OID project. The tallies show how many fish made it to the spawning grounds, but not the number that go on to successfully reproduce.
Experts said the generally strong returns to Central Valley rivers this fall resulted in part from good conditions in the Pacific, where the fish live for two to five years. The numbers also could reflect the suspension of commercial fishing in 2008 and 2009.
High river flows at the right times can help, whether to carry young salmon out to sea in spring or to attract returning adults to their native streams in fall.
The fish that came back this autumn had varied river conditions. The older ones dealt with the 2007-09 drought. The younger ones enjoyed a wet 2010.
High flows help keep the water cool enough for salmon and dilute pollution, said J.D. Wikert, a habitat restoration coordinator on the Stanislaus for the U.S. Fish and Wildlife Service. The churning also increases "turbidity," a cloudiness in the water that screens young salmon from predators, he said.
Demand for water
Full natural flows are not possible, given the demand for water for farms and cities, so habitat projects that do not rely primarily on flow can be crucial. Irrigation districts also urge controls on nonnative striped bass, which prey on salmon, and on pollution from sewer systems and other sources.
The Fish and Wildlife Service paid the other half of the cost of the OID habitat project, which was completed in September. It took place on a half-mile stretch known as Honolulu Bar, just off Orange Blossom Road about five miles from Oakdale.
Guignard, who works for FISHBIO, said gold mining long ago disturbed much of the native gravel in this stretch. Part of the project involved scooping up about 13,000 cubic yards of the gravel and placing it back in the riverbed in a way that aids spawning.
Even more important, Guignard said, was restoring year-round flows to a side channel that sometimes dried up.
And the crews re-created a floodplain that will be submerged when the river rises in spring. Young salmon will find food and shelter from predators in this area, which will be shaded by about 4,000 native trees planted with the help of River Partners, a restoration group.
Wikert said this "rearing habitat" is essential if the fish are to survive their ocean odyssey and return in a few years to spawn.
Advocates for the fish keep another count each fall the number of people attending the annual Salmon Festival in Knights Ferry. It reached 1,800 this year, Wikert said.
"The people who actually know we have salmon in the Central Valley are interested in seeing their survival," he said.
Bee staff writer John Holland can be reached at firstname.lastname@example.org or (209) 578-2385.
RANGE: California is at the southern end of the chinook's natural range along the West Coast of North America. Before dams and other human impacts, the fish swam far up the foothill portions of the Stanislaus, Tuolumne and other rivers that drain the Central Valley.
SIZE: Chinook typically grow to as long as 36 inches, although sometimes more.
LIFE CYCLE: Fall-run chinook, the most numerous salmon in the valley, lay eggs in the rivers in autumn. The juvenile fish head out the next spring to spend two to five years in the ocean. They return to the rivers to reproduce in fall of their final year.
DIET: Chinook eat insects and crustaceans while young, primarily smaller fish when older.
NUMBERS: The valley's fall-run chinook population, estimated at more than 750,000 in 2002, plummeted to about 70,000 in 2008 but has rebounded somewhat. The vast majority both years were in the Sacramento Valley.